مهدی محمدی

Aurantiochytrium sp. is a marine microalga known for its bioactive compounds. This study assessed its presence in Iran and investigated its specifc biochemical and molecular traits. Parameters such as biomass, protein content, hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels, catalase enzyme (CAT) activity, and expression of malic enzyme (ME) and acetyl-CoA carboxylase (ACCase) genes were analyzed at diferent growth stages (24, 48, 72, and 96 h). Fatty acid composition, unsaturated fatty acids (UFA) and saturated fatty acids (SFA) contents, and the ratio of UFA to SFA were also examined. Molecular identifcation confrmed successful proliferation, with signifcant increases in biomass and protein content during growth. Elevated H2O2 and MDA levels indicated oxidative stress, whereas enhanced CAT activity suggested its potential role in scavenging reactive oxygen species and mitigating oxidative damage. The upregulation of ME and ACCase genes during growth indicated their involvement in lipid biosynthesis. This was further supported by the analysis of fatty acid composition, which revealed a higher proportion of UFA than SFA. These fndings underscore the importance of specifc growth stages for optimizing cultivation conditions and maximizing bioactive compound production in Aurantiochytrium sp. Overall, this study provides valuable insights into the growth dynamics and lipid metabolism of Aurantiochytrium sp., contributing to our understanding of its potential applications.